pngcheck verifies the integrity of PNG, JNG and MNG files (by checking
the internal 32-bit CRCs [checksums] and decompressing the image data); it
can optionally dump almost all of the chunk-level information in the image
in human-readable form. For example, it can be used to print the basic
statistics about an image (dimensions, bit depth, etc.); to list the color
and transparency info in its palette (assuming it has one); or to extract
the embedded text annotations. This is a command-line program with batch
capabilities.

The current release supports all PNG, MNG and JNG chunks, including the newly approved sTER stereo-layout
chunk. It correctly reports errors in all but two of the images in Chris
Nokleberg's brokensuite-20061204. Also included (since version 2.1.0) are two helper
utilities: